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      <title>Zookeeper如何处理脑裂现象？ - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Zookeeper如何处理脑裂现象？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
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                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
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      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，分布式系统中的“脑裂”（Split-Brain）现象最核心的特征是什么？",
    "options": [
      "系统中出现多个节点都认为自己是主节点（Leader）",
      "所有节点都宕机导致服务不可用",
      "网络延迟导致客户端请求超时",
      "系统中的数据被完全清空"
    ],
    "correctAnswerIndex": 0,
    "explanation": "脑裂的核心问题在于网络分区导致集群被分割成多个部分，每个部分都无法与其他部分通信，并独立选举出自己的主节点，从而破坏了分布式系统中“单一主节点”的原则，导致数据不一致。",
    "source": "文档中「脑裂现象概述」部分",
    "hint": "文档中提到：'脑裂现象指的是在一个分布式系统中...某些节点无法与其他节点通信，从而导致多个节点认为自己是“主节点”或“领导者”。'"
  },
  {
    "question": "在 ZooKeeper 的 Leader 选举过程中，当多个节点的 Zxid（ZooKeeper 事务 ID）相同时，选举的决定性因素是什么？",
    "options": [
      "节点的网络延迟，延迟最低的节点获胜",
      "节点的 ID，ID 较大的节点会被选为 Leader",
      "节点的内存大小，内存最大的节点获胜",
      "随机选择一个节点作为 Leader"
    ],
    "correctAnswerIndex": 1,
    "explanation": "ZooKeeper的选举规则是分优先级的。首先比较Zxid，Zxid最高的节点胜出。只有在Zxid相同的情况下，才会比较节点ID（myid），此时ID较大的节点会被选为Leader。",
    "source": "文档中「选举机制」部分的「选举规则」",
    "hint": "选举规则中提到，当首要比较条件相同时，会有一个次要的比较标准。请在文档的“选举规则”中查找这个次要标准。"
  },
  {
    "question": "ZooKeeper 的心跳机制中，“Session Timeout”扮演了什么关键角色？",
    "options": [
      "它决定了Leader向Follower发送心跳的固定频率",
      "它指定了事务日志写入磁盘的最长等待时间",
      "它定义了一个时间窗口，如果服务器在此期间未收到客户端心跳，则认为该客户端会话失效",
      "它设置了Leader选举过程必须完成的最长时间"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Session Timeout是客户端与服务器之间会话有效性的核心判断依据。客户端需要在此超时时间内至少发送一次心跳来维持会话，否则服务器会认为客户端已断开连接或崩溃，并清理其相关资源（如临时节点）。",
    "source": "文档中「心跳机制」部分的「ZooKeeper 心跳机制的实现」",
    "hint": "在心跳机制的实现小节中，查找关于客户端与服务器连接会话（Session）的描述。"
  },
  {
    "question": "关于 ZooKeeper 的事务日志（transaction log）和快照（snapshot），以下描述哪项是正确的？",
    "options": [
      "快照记录了每一次写操作，而事务日志是定期生成的数据摘要",
      "ZooKeeper只依赖事务日志进行恢复，快照仅用于数据备份",
      "事务日志是内存中的临时记录，而快照是持久化到磁盘的唯一数据",
      "快照是某个时间点数据的全量备份，用于加速故障恢复，而事务日志记录了自上次快照以来的所有增量写操作"
    ],
    "correctAnswerIndex": 3,
    "explanation": "ZooKeeper通过结合使用快照和事务日志来实现高效的故障恢复。恢复时，节点首先加载最新的快照恢复大部分数据，然后重放该快照之后记录的事务日志，以达到最新的数据状态。这种方式避免了从头开始重放所有历史日志，大大提高了恢复速度。",
    "source": "文档中「事务日志和快照」部分",
    "hint": "文档中描述了这两者如何协同工作以实现高效的崩溃恢复。思考一下恢复时是先加载哪个，再应用哪个。"
  },
  {
    "question": "根据文档，ZAB 协议（ZooKeeper Atomic Broadcast）在 ZooKeeper 中主要保证了什么？",
    "options": [
      "系统的超低延迟读写性能",
      "数据的一致性和系统的高可用性",
      "客户端与服务器之间的网络通信加密",
      "简化分布式编程的API接口设计"
    ],
    "correctAnswerIndex": 1,
    "explanation": "ZAB 协议是 ZooKeeper 的核心，它是一种原子广播协议，确保了所有写操作的全局顺序和一致性。同时，它也包含了Leader选举、崩溃恢复等机制，从而保证了整个集群的高可用性。",
    "source": "文档中「ZooKeeper 的设计目标」部分的「提供高可用性」",
    "hint": "在“ZooKeeper 的设计目标”一节中，ZAB协议被提及用来保证哪两个关键特性？"
  },
  {
    "question": "当 ZooKeeper 集群的 Leader 节点发生故障时，系统会触发一系列恢复机制。根据文档描述，这个过程的第一步通常是什么？",
    "options": [
      "所有 Follower 节点立即停止服务并等待管理员手动干预",
      "客户端会自动尝试连接到另一个数据中心的备用集群",
      "剩余的 Follower 节点启动新一轮的 Leader 选举过程",
      "系统从最新的快照中恢复所有数据到 Leader 故障前的状态"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Leader节点的失效是分布式系统中的一个严重故障。ZooKeeper的设计确保了高可用性，其故障恢复机制的首要任务就是尽快选举出一个新的Leader来接管职责，以保证写服务能够继续进行。一旦新Leader确立，后续的状态同步才会开始。",
    "source": "文档中「故障检测和恢复」部分的「故障恢复」",
    "hint": "在“故障恢复”一节中，描述了当 Leader 失效后，系统会做什么来选举新的 Leader。"
  },
  {
    "question": "ZooKeeper 为什么要在执行数据变更前，先以“追加（append-only）”的形式将操作写入事务日志？",
    "options": [
      "为了提高读操作的性能，因为追加写比随机写更快",
      "为了确保所有写操作都被可靠地持久化，防止因节点崩溃导致数据丢失",
      "为了方便管理员随时回滚到任意一个历史版本",
      "为了限制同时可以执行的写操作数量，起到限流作用"
    ],
    "correctAnswerIndex": 1,
    "explanation": "这种策略被称为预写日志（Write-Ahead Logging, WAL）。通过先将变更操作记录到持久化的日志中，再更新内存中的数据，系统可以保证即使在更新内存数据过程中发生崩溃，也能通过重放日志来恢复数据，从而确保了操作的原子性和持久性。",
    "source": "文档中「事务日志和快照」部分的「事务日志的作用」",
    "hint": "文档中对事务日志的描述是“系统的日记本”，思考一下写日记的首要目的是什么。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
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          optionsListEl.innerHTML = '';
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            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

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            showResult(isCorrect, currentQuestion);
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            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

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            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
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            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
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            }
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            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
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        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  